Abstract

Language skills are central to our everyday living, but can be significantly impacted by neurological diseases, such as Semantic Dementia (SD). To date, very little has been offered to patients suffering this condition, despite their relatively preserved everyday memory, attention, and willingness to seek help. Effective assessment methods and approaches to restore vocabulary were investigated in this thesis, with a focus on the utility of word retraining to deliver meaningful and lasting benefits. Chapter 3 showed that Semantic Dementia patients could clearly be distinguished from patients with other progressive language disorders, using a short battery of tests which assess single-word processing skills. Chapter 4 demonstrated that, following an intensive word-retraining program, SD patients with mild, as well as severe, semantic impairments were able to improve their naming abilities using a simple, repetitive practice to relearn words. These investigations were expanded further in Chapter 5, where improvements in picture naming were shown to extend also to other tasks using these same words, including both expressive and comprehension based tasks. This transfer of skills was strongest for the milder patients, but could also occur to some extent when patients were more severely impaired. Chapter 6 established that ongoing benefits could be observed if participants engaged in a less intense, revision practice, following the initial training period, despite the neurodegenerative nature of the disease. Thus, cognitive intervention could provide an effective, meaningful and lasting benefit to these patients. Finally, Chapter 7 demonstrated that SD patients were aware of having language problems, but not of specific deficiencies in language content. In particular, SD patients were prone to making errors regarding past knowledge for everyday words and in even being aware if specific object-related words existed. The work within this thesis carries important clinical implications for the characterisation and management of patients with SD. In the absence of disease-modifying treatments, simple cognitive interventions provide a viable option to reduce the impact of language impairments.